Thursday, 14 August 2014 11:40

The new 500mm Rotoflux® flux leakage test system for large diameter OCTG tube and pipe.

Meeting one of its biggest challenges to date, Magnetic Analysis Corporation (MAC) recently completed and successfully passed pre-acceptance for a new 500mm (19.6”) Transverse/Longitudinal Flux Leakage Rotoflux® test system that is destined for a new tube mill at a major OCTG producer in Russia.

2014-08-14 114000 mac

500mm Rotoflux® Transverse and Longitudinal Flux Leakage System,
shown in Östersund, Sweden following final checkout for shipment to
a Russian OCTG tube mill. The Rotoflux Transverse tester, shown at center,
is temporarily moved out for ready access during maintenance operations.

The vertical element hanging in front of the face of the Transverse unit is
an add-on crane that's used to move the heavy pole pieces, when adjusting
for changes in tube dimensions.

The 500mm size rotary is the largest diameter MAC has developed and it required new mechanical designs to provide for the greater magnetization and detection capabilities, along with substantially new software. Initial assembly of the two flux leakage units was handled in MAC’s plant in Elmsford, NY, US, with final assembly, adjustments, and check out of the entire system taking place in MAC’s subsidiary Magnetic Analysis Nordic’s Östersund, Sweden plant. Additionally, a new Demagnetizer design was implemented to meet the customer’s requirements.

This 500mm system also features MAC’s latest wireless transmission of test signals between the test probes and the rotating head, a major improvement over traditional transmission by brushes and rings. The result is superior performance, lower maintenance costs and downtime, and less noise.

Flux leakage technology is well suited for inspecting high-permeability ferromagnetic metals such as heavy wall carbon steel pipe used in the oil and gas industry. MAC’s Rotoflux® can detect seams, laps, pits, scabs, rolling skins, cracks, weld line defects, and transverse and longitudinal defects as small as 5% of the wall on the OD and ID, allowing pipe producers to meet critical API 5CT, 5L, and ASTM E570 requirements.   As the oil and gas industry has expanded in recent years with the development of new fields and extraction techniques, the demand for high quality tube and pipe that meets industry standards has grown dramatically.

During the test, the pipe first passes through the multiplexed 48 channel Rotoflux® TRFX Transverse flux leakage rotary where it receives a high level of magnetic saturation which creates intense magnetic flux flow within the material. Some of this flux extends or “leaks” beyond the tube surface when interrupted by a surface or internal defect. This “leakage flux” generates test signals which are detected by the test probes rotating around the pipe. The signals are wirelessly channeled to the Rotoflux® test electronics for analyzing, processing, and data management, followed by display in real time vivid color on screen. The pipe then passes through the multiplexed 24 channel Rotoflux LRFX longitudinal rotary to detect signals from longitudinally oriented seam type defects , followed by a Demagnetizer to remove any residual magnetization.  A fully automated flaw tracking system with end suppression is used to control output sorting, alarm and marker functions.

This 500mm system is designed to handle tube and pipe ranging in size from 125mm to 500mm (5” – 19.6”) with wall thickness of 6mm – 40mm (.23” – 1.57”) at speeds that can range up to 60m/m (200 fpm), depending on the wall thickness of the test pipe. Straight or upset ends can be successfully tested. The testers are mounted on constant center automated triple drive roll benches that adjust to align the testers and drives with the level of the incoming test material, an important requirement for accurate tests. MAC also has 190mm and 360mm model Rotoflux rotaries for smaller diameter tube.

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